83. Astragalus rupertii Villarreal & M. A. Carranza, Brittonia 46(4): 335. 1994

Type:— MEXICO, Coahuila, Mpio. de Saltillo, Estación Vega, carr. 40, aprox. 8 km W de Saltillo, 1800 m, 5 Jun 1992, J. A. Villarreal 6644, 311. M. A. Carranza, D. E.

Lozano & S. Comparán. (holotype: MEXU 00640825!; isotype: NY00887990!, TEX 00000534!, CIIDIR043799 digtial image!).

Perennial. Stems up to 50 cm long, erect or ascending, pubescence dense, white-villous, trichomes up to 0.8 mm long, straight, dense. Stipules 2–5 mm long, free, triangular, lanceolate, the lowest ones slightly auriculate. Leaves 5–8 cm long, leaflets 17–23, 5–20 mm long, elliptic to obovate, retuse, adaxially appressed and scattered pubescent, abaxially similar, but denser. Peduncles 5–15 cm long, straight or incurved; the racemes 3–10 cm long, lax, flowers 10–20. Flowers blue-violet, basally whitish, ascending to deflexed with age; the calyx 8 × 3.5 mm, strigose, trichomes black short, and longer white ones scattered, the tube 3–5 mm long, urceolate to oblong-urceolate, the teeth 3 mm long, triangular or subulate; the banner 14 × 6 mm, oblanceolate, retuse; the wings 12 × 2 mm, the claw 4 mm long, the blade 8 mm long, oblong to oblanceolate; the keel 9 × 3.5 mm, the claw 4 mm long, the blade 5 mm long, straight or obliquely apically. Pod 6 × 4 mm, susbsessile or minute stipitate, oblique, elliptic to sub-oblong, widened, but not inflated like a bladder, laterally compressed, basally wide-rounded, distally contracted abruptly in a short triangular beak and the style persistent for a period of time, ventrally sulcate along the suture, dorsally wide and openly sulcate, the valves rigid, scattered strigose, septum complete, the pod thence bilocular; ovules 4; seeds 2.3 mm long, mitten shaped, brown-reddish, smooth, shiny.

Distribution:— Endemic to Mexico, exclusively in Coahuila, recorded only at two localities in the southeastern part of the state, in Saltillo and General Cepeda (Fig. 24).

Habitat:— Locally abundant in some localities, in chaparral and disturbed vegetation, maguey thickets, and oaks; 1600–1950 m.

Comments:— Excluding the species with dolabriform pubescence, triquetrouss pods and those with different but stipitate pods, the geopolitical border between Nuevo León and Coahuila, harbor three other species with widened, sessile pods, A. diphacus, A. mollissimus, and A. pomphocalyx. The pod of A. diphacus is didymous (pod stongly constricted dorsoventrally in the central part, constituting two inflated chambers, the pod notched at apex), A. mollissimus can be discerned by its relatively large leaves (the largest at least 12 cm long), larger petals (banner 15.3– 25 mm, wings 14.5–20 mm, keel 11–13.6 mm) than the other species. Astragalus pomphocalyx and A. rupertii possess widened, subglobose, oblique-elliptic to sub-oblong, relatively small (6–8 × 4–6 mm, long and wide respectivelly) and pubescent pods. However, A. pomphocalyx has shorter (or almost as long as leaves, rarely surpassing them) peduncles (3–5 cm long), compact racemes even at maturity, 2–5 cm long, and among the most distinctive characteristic is its strongly urceolate-globose calyx, 9–10 mm long, with dense white strigose pubescence, contrasting characteristics with A. rupertii.

Specimens examined:— COAHUILA: 4 September 1992, Gral. Zepeda, J. A. Villarreal 6701 a, M. A. Carranza, J. Valdés (ANSM, MEXU, TEX-LL); 5 June 1992, 8 km O de Saltillo, Coahuila, J. A. Villarreal 6601, M. A. Carranza (ANSM, CIIDIR); 1 April 1992, General Cepeda, 30 km W, J. Neff 92-4-1-2 (NY, TEX-LL); 5 June 1992, Estación de Microondas Vega, 8 km W de Saltillo, Carr. (40), J. Villarreal Q. 6656 & 6654, M. Carranza, S. Comparán, D. E. Lozano (ANSM, NY); 5 June 1992, Saltillo, J. A. Villarral 6601 & 6622 b, M. A. Carranza, S. Comprarán, D. E. Lozano (MEXU).